CN108882316B

CN108882316B - Cell switching method, terminal, base station equipment and communication system

Info

Publication number: CN108882316B
Application number: CN201710326023.5A
Authority: CN
Inventors: 刘亚林; 樊波
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-05-10
Filing date: 2017-05-10
Publication date: 2021-11-19
Anticipated expiration: 2037-05-10
Also published as: CN108882316A; CN114222332A; WO2018205965A1

Abstract

The invention discloses a cell switching method, a terminal, base station equipment and a communication system, wherein the method comprises the following steps: the terminal judges whether the switching condition of switching from the current cell to the target cell is met, wherein the switching condition comprises at least one of failure of a wireless link, failure of the terminal to continuously send uplink data to the source base station for a preset number of times, failure rate of the terminal to send the uplink data to the source base station within a preset time length higher than a preset threshold value, and signal intensity of the target cell higher than that of the cell where the terminal is currently located; and when the switching condition is met, the terminal sends an access request to a target base station, wherein the target base station is the base station of the target cell. According to the invention, through setting various switching conditions, the switching conditions of the terminal during cell switching are more comprehensive, the communication condition between the terminal and the base station can be more comprehensively reflected, the problems in the actual communication scene can be better solved, and the success probability of the terminal during cell switching is improved.

Description

Cell switching method, terminal, base station equipment and communication system

Technical Field

The present invention relates to the field of communications, and in particular, to a cell switching method, a terminal, a base station device, and a communication system.

Background

In a wireless communication system, a terminal reports signal measurement information to a base station of a current cell, the base station sends a cell switching command to the terminal according to the signal measurement information, and the terminal is switched to an adjacent cell according to the cell switching command. However, when the terminal is located at the edge of the cell, the quality of the radio link between the terminal and the current cell is generally poor, which may cause the cell handover command to be lost, that is, the terminal may not receive the cell handover command sent by the base station of the current cell, thereby causing the handover failure.

Disclosure of Invention

In view of this, the present application provides a cell handover method, a terminal, a base station device and a communication system, and aims to improve the success probability of the terminal in cell handover.

In a first aspect, a cell handover method is provided, where the method includes: the terminal judges whether a switching condition for switching from the current cell to a target cell is met, wherein the switching condition comprises at least one of radio link failure, failure of the terminal to continuously send uplink data to the base station of the current cell for a preset number of times, failure rate of the terminal to send the uplink data to the base station of the current cell within a preset time length higher than a preset threshold value, and signal intensity of the target cell higher than the signal intensity of the cell in which the terminal is currently located; and when the switching condition is met, the terminal sends an access request to a target base station, wherein the target base station is the base station of the target cell. In the method, by setting various switching conditions, the switching conditions of the terminal during cell switching are more comprehensive, the problems in the actual communication scene can be better solved, and the probability of switching failure is reduced. For example, if the terminal only uses the signal strength of the target cell higher than the signal strength of the cell in which the terminal is currently located as the only handover condition, it may still be the case that the uplink channel quality is poor and the information transmission failure rate is high when the signal strength of the cell in which the terminal is currently located is good enough, and at this time, the terminal also needs to perform cell handover. And the communication condition between the terminal and the base station can be further reflected more comprehensively by three switching conditions of failure of the wireless link, failure of the terminal to send uplink data to the source base station for the continuous preset times and failure rate of the terminal to send the uplink data to the source base station within the preset time length higher than a preset threshold value.

According to the first aspect, in a first possible implementation manner of the cell handover method, the method further includes: and the terminal receives information which is sent by the base station of the current cell and used for triggering the terminal to start judging whether the switching condition is met. After the cells allowing the switching are determined or the terminal is determined to be necessary to prepare for the switching, the source base station sends information for triggering the terminal to start judging whether the switching condition is met or not to inform the terminal that the switching condition can be started, so that the terminal cannot start judging the switching condition when the cells allowing the switching are not available, the burden of the terminal is reduced, and the power consumption of the terminal is reduced.

In a second possible implementation manner of the cell handover method according to the first aspect as such or the first possible implementation manner of the first aspect, the method further includes: the terminal receives indication information sent by the base station of the current cell, wherein the indication information indicates the target base station to allocate resources for accessing the target cell for the terminal; the terminal sending the access request to the target base station comprises the following steps: and the terminal sends an access request to the target base station according to the resource allocated by the target base station.

In a second aspect, a cell handover method is provided, where the method includes: after receiving cell measurement information sent by a terminal, a source base station sends a switching preparation request to base stations of all alternative cells; a source base station receives switching preparation confirmation information fed back by a target base station, wherein the target base station is a base station of a target cell, and the target cell is an alternative cell which allows terminal switching in each alternative cell; after receiving the switching preparation confirmation information, the source base station sends information for triggering the terminal to start judging whether the switching condition of switching from the current cell to the target cell is met or not to the terminal; the switching condition comprises at least one of radio link failure, failure of sending uplink data to the source base station for continuous preset times by the terminal, failure rate of sending the uplink data to the source base station within preset time length by the terminal higher than a preset threshold value, and signal intensity of the target cell higher than that of the cell where the terminal is located currently. Firstly, after the source base station determines that the cell which allows the switching exists or after the terminal is determined to be necessary to prepare the switching, the source base station sends information which is used for triggering the terminal to start judging whether the switching condition for switching from the current cell to the target cell is met, and informs the terminal that the switching condition can be started to judge, so that the terminal cannot start judging the switching condition when the cell which allows the switching does not exist, and the burden of the terminal is reduced. In addition, by setting various switching conditions, the switching conditions of the terminal during cell switching are more comprehensive, the problems in an actual communication scene can be better solved, and the probability of switching failure is reduced.

In a first possible implementation manner of the cell handover method according to the second aspect, the information for triggering the terminal to start determining whether a handover condition for a current cell to handover to the target cell is satisfied includes: and indicating the target base station to allocate the resources for accessing the target cell to the terminal.

In a second possible implementation manner of the cell handover method according to the second aspect or the first possible implementation manner of the second aspect, the method further includes: and after the terminal is successfully accessed or switched, the source base station sends information for indicating to release the resources allocated to the terminal to other target base stations except the base station where the cell where the terminal is successfully accessed or switched is located. Therefore, the resources of other target cells can be released in time after the terminal completes access or switching, and the resource waste of other target cells is effectively avoided.

In a third possible implementation manner of the cell handover method according to the second aspect as such or any one of the implementation manners of the second aspect above, the method further includes: the source base station starts timing after receiving the cell measurement information sent by the terminal or after sending the switching preparation request to the target base station; and when the timing reaches a first preset time length, if the source base station does not receive any message indicating that the terminal is successfully accessed or switched to the target cell, the source base station sends information for indicating to release the resources allocated to the terminal to all the target base stations. In the method, the source base station is used for timing, if the terminal is not successfully accessed within the preset time length, the source base station can timely inform each target base station to release the resources distributed for the terminal and communicated in each target cell, the resources of each target cell are released in time, and the resource waste of each target cell is effectively avoided.

In a fourth possible implementation manner of the cell handover method according to the second aspect as such or any one of the implementation manners of the second aspect above, the source base station sends timing information to the target base station; the timing information indicates a second preset duration for the target base station to wait for releasing the resources allocated to the terminal. In the method, the timing information is sent to the target base station, so that the target base station can time and release resources by itself without the need of additionally informing the source base station of releasing the resources.

In a third aspect, a cell handover method is provided, where the method includes: after receiving cell measurement information sent by a terminal, a source base station sends a switching preparation request to a base station of an alternative cell; a source base station receives switching preparation confirmation information fed back by a target base station, wherein the target base station is a base station of a target cell, and the target cell is an alternative cell which allows terminal switching in each alternative cell; and after the terminal is successfully accessed or switched, the source base station sends information for indicating to release the resources allocated to the terminal to other target base stations except the base station where the cell where the terminal is successfully accessed or switched is located. Therefore, the resources of the target cell of the terminal which is not successfully accessed or switched can be released in time after the terminal completes access or switching, and the resource waste of the target cell of the terminal which is not successfully accessed or switched is effectively avoided.

According to the third aspect, in a first possible implementation manner of the cell handover method, the method further includes: the source base station starts timing after receiving the cell measurement information sent by the terminal or after sending the switching preparation request to the target base station; and when the timing duration reaches a first preset duration, if the source base station does not receive any message indicating that the terminal is successfully accessed or switched to the target cell, the source base station sends information for indicating to release the resources allocated to the terminal to all the target base stations. In the method, the source base station is used for timing, if the terminal is not successfully accessed within the preset time length, the source base station can timely inform each target base station to release the resources distributed for the terminal and communicated in each target cell, the resources of each target cell are released in time, and the resource waste of each target cell is effectively avoided.

According to the third aspect or the first possible implementation manner of the third aspect, in a second possible implementation manner of the cell handover method, the method further includes: the source base station sends timing information to the target base station; the timing information indicates a second preset duration for the target base station to wait for releasing the resources allocated to the terminal. In the method, the timing information is sent to the target base station, so that the target base station can time and release resources by itself without the need of additionally informing the source base station of releasing the resources.

According to the third aspect or the first and second possible implementation manners of the third aspect, in a third possible implementation manner of the cell handover method, the method further includes: when the timing duration reaches a first preset duration, if the terminal is not successfully accessed or switched to any target cell in the timing stage, the source base station sends a switching preparation request to the base station of the alternative cell again; and when the first preset time length is met, the timing ending moment is consistent with the timing information or the moment indicated by the timing information.

It is to be understood that the third aspect, the first possible implementation manner of the third aspect, the second possible implementation manner of the third aspect, and the third possible implementation manner of the third aspect may all be implemented separately as an independent scheme, or may be implemented in combination with each other.

In a fourth aspect, a cell handover method is provided, where the method includes: the target base station receives information which is sent by a source base station and indicates to release resources allocated to the terminal; and the target base station releases the resources distributed to the terminal.

According to a fourth aspect, in a first possible implementation manner of the cell handover method, the method further includes: the target base station allocates resources for the terminal; the target base station starts timing; and when the timing duration reaches a second preset duration, if the target base station does not receive the access request sent by the terminal in the timing stage, releasing the resources allocated to the terminal by the target base station.

According to the fourth aspect or the first possible implementation manner of the third aspect, in a second possible implementation manner of the cell handover method, the method further includes that the target base station receives timing information sent by the source base station, where the timing information indicates the second preset duration.

It is understood that the fourth aspect, the first possible implementation manner of the fourth aspect, and the second possible implementation manner of the fourth aspect may be implemented individually as an independent solution, or may be implemented in combination with each other.

In a fifth aspect, a terminal is provided, where the terminal includes a processor and a transceiver, and the processor is configured to determine whether a handover condition for handover from a current cell to a target cell is satisfied, where the handover condition includes at least one of a radio link failure, a failure rate of the terminal to send uplink data to a base station of the current cell for a preset number of times is higher than a preset threshold, and a signal strength of the target cell is higher than a signal strength of the cell where the terminal is currently located; the transceiver is configured to send an access request to a target base station when the handover condition is satisfied, where the target base station is a base station of the target cell. The terminal sets various switching conditions, so that the switching conditions of the terminal during cell switching are more comprehensive, the problem in an actual communication scene can be solved, and the probability of switching failure is reduced. For example, if the terminal only uses the signal strength of the target cell higher than the signal strength of the cell in which the terminal is currently located as the only handover condition, it may still be the case that the uplink channel quality is poor and the information transmission failure rate is high when the signal strength of the cell in which the terminal is currently located is good enough, and at this time, the terminal also needs to perform cell handover. And the communication condition between the terminal and the base station can be further reflected more comprehensively by three switching conditions of failure of the wireless link, failure of the terminal to send uplink data to the source base station for the continuous preset times and failure rate of the terminal to send the uplink data to the source base station within the preset time length higher than a preset threshold value.

In a sixth aspect, a base station device is provided, the base station device comprising a processor and a transceiver; the transceiver is used for receiving cell measurement information sent by a terminal; the processor is used for controlling the transceiver to send a switching preparation request to the base station of each alternative cell after the transceiver receives the cell measurement information; the transceiver is further configured to receive handover preparation confirmation information fed back by a target base station, where the target base station is a base station of a target cell, and the target cell is an alternative cell that allows terminal handover among the alternative cells; the processor is further configured to control the transceiver to send, to the terminal, first information for triggering the terminal to start determining whether a handover condition for switching from a current cell to the target cell is satisfied, after the transceiver receives the handover preparation confirmation information; the switching condition comprises at least one of radio link failure, failure of sending uplink data to the base station equipment by the terminal for continuous preset times, failure rate of sending the uplink data to the base station equipment by the terminal within preset time length higher than a preset threshold value, and signal intensity of the target cell higher than that of the cell where the terminal is located currently.

In a seventh aspect, a base station device is provided, the base station device comprising a processor and a transceiver; the processor is used for controlling the transceiver to send a switching preparation request to the base station of the alternative cell after receiving the cell measurement information sent by the terminal; the transceiver is further configured to receive handover preparation confirmation information fed back by a target base station, where the target base station is a base station of a target cell, and the target cell is an alternative cell that allows terminal handover among the alternative cells; the processor is further configured to control the transceiver to send, to each of the other target base stations other than the base station where the cell where the terminal successfully accesses or switches is located, information for instructing to release the resource allocated to the terminal after the terminal successfully accesses or switches.

According to the seventh aspect, in a first possible implementation manner of the base station device, the processor is further configured to start timing after receiving the cell measurement information sent by the terminal or after sending the handover preparation request to the target base station; and when the timing duration reaches a first preset duration, if the transceiver does not receive any message indicating that the terminal is successfully accessed or switched to the target cell, the transceiver is further configured to send information indicating to release the resources allocated to the terminal to all the target base stations.

It is understood that the first possible implementation manners of the seventh aspect and the seventh aspect may be implemented individually as an independent scheme, or may be implemented in combination with each other.

In an eighth aspect, there is provided a base station device comprising a processor and a transceiver; the transceiver is used for receiving the information which is sent by the source base station and indicates to release the resources allocated to the terminal; the processor is configured to release the resources allocated to the terminal.

In a first possible implementation manner of the base station device according to the eighth aspect, the processor is further configured to allocate resources to a terminal; the processor is also used for starting timing; and when the timing duration reaches a second preset duration, if the transceiver does not receive the access request sent by the terminal in the timing stage, the processor releases the resources allocated to the terminal.

It is understood that the above-mentioned eighth aspect and the first possible implementation manner of the eighth aspect may be implemented individually as an independent solution, or may be implemented in combination with each other.

In a further aspect of the present invention, there is provided a communication system comprising the terminal and the base station apparatus described in the above aspect.

In still another aspect of the present invention, a computer-readable storage medium is provided, which stores computer software instructions for the terminal, which when run on a computer, cause the computer to perform the method of the above aspects.

In yet another aspect of the present invention, a computer-readable storage medium is provided, which stores computer software instructions for the base station apparatus described above, and when the computer software instructions are executed on a computer, the computer is caused to execute the method of the above aspects.

Drawings

FIG. 1 is an exemplary diagram of a communication system in accordance with one embodiment of the present invention;

fig. 2 is an exemplary flowchart of a cell switching method according to an embodiment of the present invention;

fig. 3 is another exemplary flowchart of a cell switching method according to an embodiment of the present invention;

fig. 4 is a flowchart illustrating a method for cell handover according to an embodiment of the present invention;

fig. 5 is a further exemplary flowchart of a cell switching method according to an embodiment of the present invention;

fig. 6 is a diagram illustrating an exemplary hardware structure of a terminal according to an embodiment of the present invention;

fig. 7 is a schematic diagram of an exemplary hardware structure of a base station device according to an embodiment of the invention.

Detailed Description

The technical solutions of the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention.

The technical solutions of the embodiments of the present invention described below can be applied to a communication system. The communication system may comprise at least one base station, and terminal equipment in communication with at least one of said base stations, and the base stations may also communicate with each other.

The Base Station may be a Base Transceiver Station (BTS) in a GSM (Global System for Mobile Communication) or CDMA (Code Division Multiple Access) network, an nb (nodeb) in a WCDMA (Wideband Code Division Multiple Access) network, an eNB or enodeb (evolved nodeb) in an LTE (Long Term Evolution), a Base Station in a future 5G network, a Base Station in a future Communication System, or the like.

A terminal can be a UE (User Equipment), an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote terminal, a mobile device, a User terminal, a wireless communication device, a User agent, or a User Equipment, etc. The access terminal may be a cellular phone, a cordless phone, a SIP (Session Initiation Protocol) phone, a WLL (Wireless Local Loop) station, a PDA (Personal Digital Assistant), a handheld device with Wireless communication function, a computing device or other processing device connected to a Wireless modem, a vehicle-mounted device, a wearable device, a terminal in a future 5G network, etc.

Fig. 1 is an example of the communication system, and the communication system shown in fig. 1 includes three base stations and one terminal. Each base station includes at least one cell. For example, the present invention is described by taking an example in which each base station includes three cells. The base station of the cell in which the terminal is currently located is hereinafter referred to as a source base station.

An embodiment of the present invention provides a cell switching method, as shown in fig. 2, in a first embodiment of the cell switching method, the method includes:

s100, the terminal measures signals of the current cell and the adjacent cells.

The terminal may measure the signal strength of the reference signal and may also measure the signal strength of the synchronization signal.

S101, the terminal reports the measurement information to the source base station. The source base station is the base station of the cell where the terminal is currently located.

In an embodiment, the terminal may periodically perform signal measurement on the current cell and the neighboring cell and report measurement information.

In another embodiment, a trigger event may be predefined, and when the trigger event is satisfied, the terminal performs signal measurement on the current cell and the neighboring cell and reports measurement information. The triggering event may be the terminal detecting that the current cell signal strength is close to the neighbor cell signal strength.

In another embodiment, the method may also be triggered by the base station of the current cell, and when the base station of the current cell detects that the communication quality with the terminal is not good, the terminal may be triggered to perform signal measurement and reporting.

The measurement information can take two forms:

1. the measurement information includes signal measurement results of the currently located cell and signal measurement results of the neighboring cells. Specifically, the method may include a correspondence between a current cell identifier and a current cell signal measurement result, and a correspondence between a neighboring cell identifier and a neighboring cell signal measurement result. The signal measurement result may be a signal strength, for example, a signal strength measured for a reference signal, or a signal strength measured for a synchronization signal.

2. The terminal may not report the signal measurement result of the current cell and the signal measurement results of the neighboring cells to the source base station. The terminal can determine whether the terminal is about to need to switch according to the measurement result, and report the measurement information to the source base station when the terminal determines that the terminal is about to need to switch. When a terminal is approaching a cell edge or approaching a certain condition, the terminal may be considered to be in need of handover. The terminal may further determine, in each neighboring cell, a cell that may allow handover according to the signal measurement result of the current cell and the signal measurement results of the neighboring cells, where the measurement information includes an identifier of each cell that may allow handover, or the measurement information includes indication information for indicating each cell that may allow handover.

The terminal may calculate a difference (which may be a positive number, zero, or a negative number) between the measured signal strength of the current cell and the signal strength of each neighboring cell, find a difference smaller than a preset threshold (which may be a positive number) in each calculated difference, and determine the neighboring cell corresponding to each found difference as a cell that may allow handover. Or, the terminal may further find the maximum first N signal strengths among the measured signal strengths of the neighboring cells when the uplink data transmission fails for a preset number of times, and determine the neighboring cell corresponding to the found N signal strengths as a cell that may allow handover. For example, N may be greater than or equal to 1. N may be set according to actual needs, and is not limited herein.

When the source base station manages a plurality of cells (e.g., three), the cells that may allow handover may include cells subordinate to the source base station. Each of the cells that are likely to allow handover, except for the cell subordinate to the source base station, will be referred to as an alternative cell hereinafter. A cell subordinate to the source base station among cells that are likely to allow handover is referred to as an intra-alternative-station cell.

S102, the source base station receives the measurement information.

S103, the source base station determines alternative cells in each adjacent cell according to the measurement information.

When the measurement information adopts the above form 1, that is, the measurement information includes the signal measurement result of the cell where the measurement information is currently located and the signal measurement results of the neighboring cells, the source base station may determine the cell that may allow handover in each neighboring cell in the same manner as the terminal determines the cell that may allow handover, which is not described herein again. The method is different from the method in which the terminal determines the candidate cell according to the number of consecutive failures of sending the uplink data, and when the source base station sends the downlink data to the terminal for a preset number of consecutive failures, the source base station finds out the largest first N signal strengths from the signal strengths of the neighboring cells, and determines the neighboring cell corresponding to the found N signal strengths as a cell which is likely to allow handover. Further, the source base station determines each cell other than the cell subordinate to the source base station among the cells which are likely to allow handover as the candidate cell.

The source base station may also determine a cell subordinate to the source base station among cells that are likely to allow handover as an intra-alternative-station cell.

When the measurement information adopts the above form 2, that is, the measurement information includes the identifier of each cell that may allow handover, or includes indication information indicating each cell that may allow handover, the source base station may directly determine each cell, except for the cell belonging to the source base station, of the cells that may allow handover as the alternative cell. The source base station may also determine a cell subordinate to the source base station among cells that are likely to allow handover as an intra-alternative-station cell.

The following embodiments are described with respect to alternative cells and then with respect to cells within alternative stations.

S104, the source base station sends a switching preparation request to the base station of each alternative cell.

The handover preparation request indicates that the terminal may need to be handed over to the alternative cell soon, and the base station requiring the alternative cell allocates resources for accessing the alternative cell to the terminal.

In an embodiment, each base station manages a plurality of cells (e.g., three), and the handover preparation request may further indicate which cell under the base station the terminal may be about to need to handover to, e.g., the identity of each candidate cell.

And S105, the base station of each alternative cell receives the switching preparation request sent by the source base station and determines whether to allow the terminal to be switched to the alternative cell corresponding to the switching preparation request.

In an embodiment, the base station of each candidate cell may determine whether to allow the terminal to switch to the candidate cell according to the current load of the candidate cell corresponding to the handover preparation request. The base station of each candidate cell can also determine whether to allow the terminal to be switched to the candidate cell according to the wireless resource utilization condition of the candidate cell, the load of each network element, the QOS condition of the existing session, the QOS requirement of the newly applied wireless resource and the like.

Hereinafter, the candidate cell to which the terminal is allowed to handover among the candidate cells is referred to as a target cell, and the base station in which the target cell is located is referred to as a target base station.

S106, when the terminal switching is determined to be allowed, the target base station allocates resources for accessing the target cell for the terminal.

The resources allocated to the terminal by the target base station comprise time-frequency resources. The terminal may send the random access signaling using the time-frequency resource. The resource allocated by the target base station for the terminal may further include a Preamble index (Preamble index) and the like.

S107, the target base station feeds back switching preparation confirmation information to the source base station.

The handover preparation confirm message informs the source base station that the terminal is allowed to handover.

In an embodiment, the handover preparation acknowledgement information may indicate an alternative cell, i.e., the target cell, to which handover is allowed. For example, the handover preparation confirm message may carry the identity of the target cell.

In another embodiment, the handover preparation confirmation information may further include information indicating resources allocated by the target base station for the terminal to access the target cell.

Alternatively, the target base station may additionally indicate, through a separate message, the resources allocated by the target base station to the terminal for accessing the target cell.

When the terminal is determined not to be allowed to be switched, the base station of the alternative cell which is not allowed to be switched by the terminal can feed back corresponding indication information to the source base station so as to inform the source base station that the alternative cell is not allowed to be switched; or the indication information may not be fed back.

And S108, the source base station receives the switching preparation confirmation information fed back by the target base station.

In an embodiment, the source base station may further receive information, fed back by the target base station, indicating resources allocated by the target base station for the terminal to access the target cell.

Therefore, the source base station knows the resources which are allocated to the terminal by the target base station and are used for accessing the target cell.

S109, the source base station may send information for triggering the terminal to start determining whether the handover condition is satisfied to the terminal.

In an embodiment, the information for triggering the terminal to start determining whether a handover condition for handover from a current cell to the target cell is satisfied includes: and indicating the target base station to allocate the resources for accessing the target cell to the terminal. And after receiving the indication information, the terminal starts to judge whether the switching condition is met.

In another embodiment, the information for triggering the terminal to start determining whether the handover condition for the current cell to the target cell is satisfied may include, for example, 1-bit indication information (in other embodiments, a plurality of bits may also be used). After receiving the 1-bit indication information, the terminal starts to judge whether the switching condition is satisfied. The information for triggering the terminal to start determining whether the handover condition for the current cell to the target cell is satisfied may further include, in addition to the 1-bit indication information, information for indicating resources allocated by the target base station to the terminal for accessing the target cell.

S110, the terminal receives information which is sent by a source base station and used for triggering the terminal to start judging whether the switching condition is met.

In an embodiment, the terminal may determine, according to the information for triggering the terminal to start judging whether the handover condition is satisfied, the resource allocated by the target base station to the terminal for accessing the target cell. The overhead of the control channel is saved.

Or, in another embodiment, the terminal may receive the indication information sent by the source base station, in addition to the information sent by the source base station for triggering the terminal to start judging whether the handover condition is met. The terminal may determine, according to the indication information, resources allocated by the target base station to the terminal for accessing the target cell.

After receiving the information for triggering the terminal to start determining whether the handover condition is satisfied, the terminal starts to execute step S111.

In the invention, after the cell allowing the switching is determined, the source base station sends the information for triggering the terminal to start judging whether the switching condition is met or not to the terminal, and informs the terminal that the switching condition can be started, so that the load and the power consumption of the terminal are not reduced when the terminal does not have the cell allowing the switching.

Step S111, the terminal judges whether a switching condition for switching from the current cell to the target cell is satisfied, wherein the switching condition includes at least one of Radio Link Failure (RLF), Failure of the terminal to continuously transmit uplink data to the source base station for a preset number of times, Failure rate of the terminal to transmit the uplink data to the source base station within a preset time length being higher than a preset threshold value, and signal strength of the target cell being higher than signal strength of the current cell of the terminal.

In one embodiment, when any one of the above four conditions is satisfied, the terminal determines that the handover condition is satisfied.

According to the embodiment, through setting multiple switching conditions, the switching conditions of the terminal during cell switching are more comprehensive, the problems in an actual communication scene can be better solved, and the probability of switching failure is reduced. For example, if the terminal only uses the signal strength of the target cell higher than the signal strength of the cell in which the terminal is currently located as the only handover condition, it may still be the case that the uplink channel quality is poor and the information transmission failure rate is high when the signal strength of the cell in which the terminal is currently located is good enough, and at this time, the terminal also needs to perform cell handover. And the communication condition between the terminal and the base station can be further reflected more comprehensively by three switching conditions of failure of the wireless link, failure of the terminal to send uplink data to the source base station for the continuous preset times and failure rate of the terminal to send the uplink data to the source base station within the preset time length higher than a preset threshold value.

In an embodiment, the preset number of times may be set to 3 times, 4 times, and the like, and may be specifically set according to actual needs, which is not limited herein. Taking 3 times as an example, when the terminal fails to transmit uplink data to the source base station for 3 consecutive times, it is considered that the handover condition is satisfied.

In an embodiment, the preset duration and the preset threshold may also be flexibly set according to actual needs, which is not limited herein. The failure rate may be a ratio between the number of times that the terminal fails to send the uplink data to the source base station and the total number of times that the terminal sends the uplink data to the source base station within a preset time period.

Step S112, when the switching condition is satisfied, the terminal sends an access request to the target base station.

In an embodiment, when there are at least two target cells, the terminal may select a target cell with the best quality and send an access request to the target cell.

In an embodiment, the terminal specifically sends an access request to the target base station according to the resource allocated by the target base station.

In an embodiment, the terminal completes the initial access of the target cell through the resources allocated by the target base station.

After the terminal completes the initial access, the target base station where the target cell completing the initial access is located may feed back a message indicating that the terminal successfully accesses to the source base station. Alternatively, the message may also be fed back by the terminal to the source base station.

After receiving the message indicating the successful access of the terminal, the source base station sends information such as user context and the like to the target base station, and then the source base station releases the information such as the user context and the like. And the target base station receives the information such as the user context and the like, so that the terminal completes cell switching.

In an embodiment, after the terminal completes handover, a message indicating that the terminal successfully performs handover may be fed back to the source base station by the terminal or the target base station where the target cell completing handover is located.

It should be noted that, when the cell managed by the source base station includes the cell in the alternative station, specifically, the source base station may determine whether to allow the terminal to be switched to the cell in the alternative station according to the current load of the cell in the alternative station. The source base station may further determine whether to allow the terminal to switch to the cell in the candidate cell according to the radio resource utilization condition of the candidate cell, the load of each network element, the Quality of Service (QoS) condition of the existing session, the QoS requirement of the newly applied radio resource, and the like.

The candidate intra-station cell that allows terminal handover among the respective candidate intra-station cells may be referred to as a target intra-station cell.

The source base station may allocate resources for the terminal to access the cell within the target station. The resource may refer to the resource for accessing the target cell, and is not described herein again.

Further, based on the above embodiment, when the sum of the target cell allowed to be switched and the cell in the target station is at least two, if the terminal is successfully accessed or switched to one of the target cells or any one of the cells in the target station, the resources allocated to the terminal by the target cell not accessed to the terminal and the cell in the target station should be released in time, otherwise, the resources are wasted.

And after the terminal is successfully accessed or switched, the source base station sends information for indicating to release the resources allocated to the terminal to other target base stations except the base station where the cell where the terminal is successfully accessed or switched is located.

In an embodiment, if the cell to which the terminal successfully accesses or switches is the cell in the target station, the source base station does not need other indication information to indicate that the terminal successfully accesses or switches, and the source base station may directly determine that the terminal successfully accesses or switches.

In another embodiment, if the cell that the terminal successfully accesses or switches to is the target cell, the source base station may receive a message sent by the terminal or the target base station to indicate that the terminal successfully accesses or switches to the target cell. After receiving the message, the source base station can determine that the terminal is successfully accessed or switched.

Several embodiments of releasing resources are described below:

1. when the cell accessed or switched by the terminal is the cell in the target station:

and if the target station inner cell which is not accessed by the terminal exists, the source base station automatically releases the resources which are distributed for the terminal and used for accessing the target station inner cell which is not accessed by the terminal.

The source base station may also send information indicating to release the resources allocated to the terminal to each of the other target base stations. And after receiving the information, the target base station releases the resources allocated to the terminal.

2. When the cell accessed or switched by the terminal is the target cell, the source base station can automatically release the resource which is allocated for the terminal and used for accessing the cell in the target station, and the release mode of the resource which is allocated for the terminal by the target base station and used for accessing the target cell is as follows:

in the first embodiment, when at least two target cells belonging to the same target base station are included in the target cell allowing handover, for example, two target cells C1 and C2 belong to the same target base station B1. If the terminal is successfully accessed or switched to C1, the target base station may directly release the resources allocated to the terminal for communication in the target cell C2.

In a second embodiment, as shown in fig. 3, when there are at least two target base stations, the method further includes:

step S113, after receiving the message indicating that the terminal is successfully accessed or handed over to the target cell, the source base station sends information indicating to release the resource allocated to the terminal to each of the target base stations other than the target base station of the target cell to which the terminal is successfully accessed or handed over.

Step S114, the target base station receives the information which is sent by the source base station and indicates to release the resources allocated to the terminal, and releases the resources allocated to the terminal.

In an embodiment, after the terminal is successfully accessed or handed over, the target base station that the terminal is successfully accessed or handed over may send, to the source base station, a message indicating that the terminal is successfully accessed or handed over to the target cell. In another embodiment, the message indicating that the terminal successfully accesses or is handed over to the target cell may also be sent by the terminal to the source base station.

For example, the target cells allowing handover include C1 and C2, C1 belongs to target base station B1, and C3 belongs to target base station B2. If the terminal is successfully accessed or switched to one of the target cells, such as C1, the source base station may notify the target base station B2 to release the resources allocated to the terminal for communication at C3, so that the resources of other target cells can be released in time after the terminal completes access or switching, and resource waste of other target cells is effectively avoided.

In a third embodiment, as shown in fig. 4, the method further includes:

step S115, the source base station starts timing; it is to be understood that the timing at which the timer starts shown in fig. 4 is merely an example, and the execution timing of step S115 may be other timing after step S101.

Step S116, when the timing reaches a first preset time length, if the source base station has not received any message indicating that the terminal is successfully accessed or switched to the target cell, the source base station sends information indicating to release the resource allocated to the terminal to all the target base stations. In addition, when the timing duration reaches the first preset duration, the source base station also automatically releases the resources which are allocated to the terminal and used for accessing the cell in the target station.

In this embodiment, the terminal may not always satisfy the handover condition, and thus, the terminal may not always perform the step S112. It is also possible that the terminal satisfies the handover condition, i.e. the terminal performs said step S112, but the terminal fails to complete the access or handover successfully.

In an embodiment, the source base station may start timing after sending the handover preparation request to the target base station; or, the source base station may start timing after waiting for a certain duration after sending the handover preparation request to the target base station, where the duration of waiting for the source base station may be equal to the duration of receiving and analyzing the handover preparation request by the target base station; or, the source base station may start timing after receiving the measurement information reported by the terminal.

The first preset time period may be set according to actual needs, and is not limited herein. The first preset time is enough for the terminal to finish the access or switching time.

If the handover condition is not satisfied, the terminal cannot access the target cell or the cell in the target station, so that resources are required to be reserved in the target cell and the cell in the target station all the time, which causes serious waste. In this embodiment, the source base station performs timing, and if the terminal does not successfully access within the preset time length, the source base station may notify each target base station to release the resources allocated to the terminal for communication in each target cell in time, and release the resources in each target cell in time, thereby effectively avoiding resource waste in each target cell. And the source base station can also release the resources which are allocated for the terminal and used for accessing the cell in the target station, thereby effectively avoiding the resource waste of the cell in the target station.

In a fourth embodiment, as shown in fig. 5, the method further includes:

step S117, the source base station transmits timing information to the target base station; the timing information indicates a second preset duration for the target base station to wait for releasing the resources allocated to the terminal. It is to be understood that the time at which the source base station transmits timing information to each target base station shown in fig. 5 is merely an example. The handover preparation request carries the timing information, or the timing information may also be sent independently of the handover preparation request.

Step S118, the target base station starts timing after receiving the timing information, or starts timing after the target base station sends the handover preparation confirmation information to the source base station, or the target base station may start timing at other times; and when the timing duration reaches a second preset duration, if the terminal is not successfully accessed or switched to the target cell under the target base station in the timing stage, releasing the resources allocated to the terminal by the target base station.

In this embodiment, the terminal may not always satisfy the handover condition, and thus, the terminal may not always perform the step S112. It is also possible that the terminal satisfies the handover condition, i.e. the terminal performs said step S112, but the terminal fails to complete the access or handover successfully. As shown in fig. 5, the terminal does not successfully access or handover to the two target base stations in fig. 5 within the timing phase, so both base stations perform step S118.

In this embodiment, the timing information is sent to the target base station, so that the target base station can time and release resources by itself, and the source base station does not need to notify the source base station of releasing resources separately.

In an embodiment, the timing of the source base station and the target base station may be synchronized. The first preset time length and the second preset time length may be the same or different, as long as the timing terminating time of the source base station and the timing terminating time of the target base station are the same. For example, the source base station may transmit timing information at the nth frame. In one way, the source base station may start timing at the nth frame, and the first preset duration is assumed to be 10 frames, and the target base station completes the analysis of the timing information at the N +4 frames, and when the timing starts at the N +4 frames, and the second preset duration is assumed to be 6 frames, both the source base station and the target base station complete timing at the 10 th frame. The other mode is as follows: the source base station may start timing at the N +4 th frame, and the first preset time and the second preset time are both 6 frames, so that the source base station and the target base station complete timing at the 10 th frame.

If the terminal does not finish accessing or switching, the source base station can timely start the process of controlling the terminal to switch the cell next time (for example, restarting to receive the measurement information of the terminal and re-determining the target base station), and the target base station can release the resource at the same time, thereby effectively ensuring the consistency of the source base station and the target base station.

It should be noted that the above embodiments for releasing resources may be combined with each other.

It is to be understood that the source base station in the above embodiments may also be used as a target base station for other handover procedures. The target base station in the above embodiments may also be used as a source base station for other handover procedures.

In the fifth embodiment, different from the fourth embodiment, the source base station does not need to send timing information to the target base station, the target base station may determine the timing duration by itself, and the target base station may start timing after allocating resources, and release resources by itself if it is found that the terminal is not yet accessed when the timing duration arrives. Therefore, the target base station can release the resources by itself without the source base station sending any information, and the burden of the source base station is reduced.

The present invention also provides a terminal 100, and the terminal 100 may be the terminal described in the above embodiments. As shown in fig. 6, the terminal 100 includes a processor 110 and a transceiver 120, and the processor 110 is connected to the transceiver 120. Optionally, the terminal 100 further comprises a memory 130. The memory 130 is connected to the processor 110 and the transceiver 120, respectively. Further optionally, the terminal 100 further comprises a bus system 140. Wherein the processor 110, the transceiver 120, and the memory 130 may be connected by a bus system 140. The memory 140 may be used to store instructions, and the processor 110 may be used to execute the instructions stored by the memory 140 to control the transceiver 120 to receive and transmit signals; the memory 140 may also be used to cache data generated by the processor 110 during execution of instructions.

The processor 110 is configured to determine whether a handover condition for handover from a current cell to a target cell is satisfied, where the handover condition includes at least one of a radio link failure, a failure of the terminal 100 to send uplink data to a base station of the current cell for a preset number of times, a failure rate of the terminal 100 to send uplink data to the base station of the current cell within a preset time period being higher than a preset threshold, and a signal strength of the target cell being higher than a signal strength of the cell in which the terminal 100 is currently located;

the transceiver 120 is configured to send an access request to a target base station when the handover condition is satisfied, where the target base station is a base station of the target cell.

As can be seen from the above embodiment, the terminal 100 shown in fig. 6 performs steps S100, S101, S110, S111 and S112 in the above method embodiment. Specifically, the processor 110 performs steps S100 and S111 in the method embodiment. The transceiver 120 performs step S101, step S110 and step S112 in the method embodiment. For more details of the above steps performed by the processor 110 and the transceiver 120, reference may be made to the above description of the method embodiments, and further description is omitted here.

In the embodiment of the present invention, by setting multiple handover conditions, the handover conditions of the terminal 100 during cell handover are more comprehensive, and the problem in the actual communication scenario can be better solved, thereby reducing the probability of handover failure. For example, if the terminal 100 only uses the signal strength of the target cell higher than the signal strength of the cell in which the terminal 100 is currently located as the only handover condition, when the signal strength of the cell in which the terminal 100 is currently located is good enough, the situations that the uplink channel quality is poor and the information transmission failure rate is high may still exist, and at this time, the terminal 100 also needs to perform cell handover. And the communication status between the terminal 100 and the base station can be further reflected more comprehensively by three switching conditions of failure of the radio link, failure of the terminal 100 to send uplink data to the source base station for a preset number of times, and failure rate of the terminal 100 to send uplink data to the source base station within a preset time period being higher than a preset threshold value.

Other functions of the processor 110 and the transceiver 120 may refer to the description of the corresponding embodiments in the cell switching method, and are not described herein again.

The present invention also provides a base station apparatus 200. As shown in fig. 7, the base station apparatus 200 includes a processor 210 and a transceiver 220, and the processor 210 and the transceiver 220 are connected. Optionally, the base station apparatus 200 further includes a memory 230. The memory 230 is connected to the processor 210 and the transceiver 220, respectively. Further optionally, the base station apparatus 200 further comprises a bus system 240. Wherein the processor 210, the transceiver 220, and the memory 230 may be connected by a bus system 240. The memory 240 may be configured to store instructions, and the processor 210 may be configured to execute the instructions stored by the memory 240 to control the transceiver 220 to receive and transmit signals; the memory 240 may also be used to cache data generated by the processor 210 during execution of instructions.

Wherein, when the base station apparatus 200 functions as the above-described source base station:

the transceiver 220 is configured to receive cell measurement information sent by the terminal 100;

the processor 210 is configured to control the transceiver 220 to send a handover preparation request to the base station of each candidate cell after the transceiver 220 receives the cell measurement information;

the transceiver 220 is further configured to receive handover preparation confirmation information fed back by a target base station, where the target base station is a base station of a target cell, and the target cell is an alternative cell that allows terminal handover among the alternative cells;

the processor 210 is further configured to control the transceiver 220 to send, to the terminal 100, information for triggering the terminal to start determining whether a handover condition for handover from a current cell to the target cell is satisfied after the transceiver 220 receives the handover preparation confirmation information;

the switching condition includes at least one of a radio link failure, a failure of the terminal to send uplink data to the base station device 200 for a preset number of times, a failure rate of the terminal to send uplink data to the base station device 200 within a preset time length being higher than a preset threshold, and a signal strength of the target cell being higher than a signal strength of a cell in which the terminal is currently located. First, the base station apparatus 200, after determining that there is a cell to which handover is permitted or after determining that it is necessary for the terminal to prepare for handover, transmits first indication information to the terminal informing that the terminal can start judging a handover condition so that the terminal does not start judgment of the handover condition when there is no cell to which handover is permitted or when it is not necessary to perform cell handover, reducing the burden on the terminal. In addition, by setting various switching conditions, the switching conditions of the terminal during cell switching are more comprehensive, the problems in an actual communication scene can be better solved, and the probability of switching failure is reduced.

In another embodiment, the processor 210 is further configured to: after the terminal 100 is successfully accessed or handed over, the transceiver 220 is controlled to transmit information for instructing to release the resources allocated to the terminal 100 to each of the target base stations other than the base station where the cell where the terminal 100 is successfully accessed or handed over is located. Therefore, the resources of the target cell which is not accessed or switched by the terminal can be released in time after the terminal completes the access or switching, and the resource waste of the target cell is effectively avoided.

In another embodiment, the processor 210 is further configured to: after the transceiver 220 receives the cell measurement information sent by the terminal 100 or after the transceiver 220 sends the handover preparation request to the target base station, starting a timer to start timing; when the timing reaches the first preset time duration, if the transceiver 220 has not received any message indicating that the terminal 100 successfully accesses or switches to the target cell, the processor 210 is further configured to control the transceiver 220 to send, to all the target base stations, information indicating to release the resource allocated to the terminal. In the method, the base station device 200 performs timing, and if the terminal does not successfully access within the preset time length, the base station device 200 can timely notify each target base station to release the resources allocated for the terminal to communicate in each target cell, and timely release the resources of each target cell, thereby effectively avoiding the resource waste of each target cell.

In another embodiment, the transceiver 220 is further configured to transmit timing information to the target base station; the timing information indicates a second preset duration for the target base station to wait for releasing the resources allocated to the terminal. In the method, the timing information is sent to the target base station, so that the target base station can time and release resources by itself without the need of additionally informing the source base station of releasing the resources.

As can be seen from the above-described embodiment, when the base station apparatus 200 shown in fig. 7 is used as the source base station: steps S102, S103, S104, S108, S109, S113, S115, S116, and S117 in the above-described method embodiment are performed. Specifically, the processor 210 executes steps S103 and S115 in the above-described method embodiment. The transceiver 220 performs steps S102, S104, S108, S109, S113, S116 and S117 in the above-described method embodiments. For more details of the above steps performed by the processor 210 and the transceiver 220, reference may be made to the description of the above method embodiments, and further description is omitted here.

The processor 210 and other functions of the transceiver 220 may refer to the description of the corresponding embodiments in the cell switching method, and are not described herein again.

When the base station apparatus 200 functions as the above-described target base station:

the transceiver 220 is configured to receive information, sent by a source base station, indicating to release resources allocated to the terminal;

the processor 210 is configured to release the resources allocated to the terminal.

In another embodiment, the processor 210 is further configured to allocate resources for the terminal; processor 210 is also used to start timing; when the timing duration reaches a second preset duration, if the transceiver 220 does not receive the access request sent by the terminal in the timing phase, the processor 210 releases the resource allocated to the terminal.

As can be seen from the above-described embodiment, when the base station apparatus 200 shown in fig. 7 is used as the above-described target base station: steps S105, S106, S107, S114 and S118 in the above-described method embodiment are performed. Specifically, the processor 210 executes the step of determining whether to allow the terminal to switch in step S105, the steps of releasing the resources allocated to the terminal in steps S106 and S114, and the step of counting time in S118 in the above method embodiment. The transceiver 220 performs the step of receiving the handover preparation request in step S105, the steps of receiving information indicating release of resources allocated to the terminal in steps S107, S114, and the step of releasing resources in S118 in the above-described method embodiments. For more details of the above steps performed by the processor 210 and the transceiver 220, reference may be made to the description of the above method embodiments, and further description is omitted here.

The present invention also provides a communication system including the terminal 100 and the base station apparatus 200 described in the above embodiments. Reference may be made to the above embodiments, which are not described herein again.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

In summary, the above description is only an example of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method of cell handover, the method comprising:

after receiving information which is sent by a base station of a current cell and used for triggering the terminal to start judging whether the switching condition is met or not, the terminal starts to judge whether the switching condition for switching from the current cell to a target cell is met or not, wherein the information represents that the cells which are allowed to be switched are determined, and when at least one of a plurality of preset conditions occurs, the terminal judges that the switching condition is met, the plurality of preset conditions comprise radio link failure, failure of sending uplink data to the base station of the current cell by the terminal for continuous preset times, failure rate of sending the uplink data to the base station of the current cell within preset time by the terminal being higher than a preset threshold value, and signal intensity of the target cell being higher than signal intensity of the cell in which the terminal is currently located;

and when the switching condition is met, the terminal sends an access request to a target base station, wherein the target base station is the base station of the target cell.

2. The method of claim 1, wherein the method further comprises: the terminal receives indication information sent by the base station of the current cell, wherein the indication information indicates the target base station to allocate resources for accessing the target cell for the terminal;

the terminal sending the access request to the target base station comprises the following steps: and the terminal sends an access request to the target base station according to the resource allocated by the target base station.

3. A method of cell handover, the method comprising:

the source base station sends a switching preparation request to the base stations of all the alternative cells;

a source base station receives switching preparation confirmation information fed back by a target base station, wherein the target base station is a base station of a target cell, and the target cell is an alternative cell which allows terminal switching in each alternative cell;

after receiving the switching preparation confirmation information, the source base station sends information for triggering the terminal to start judging whether the switching condition of switching from the current cell to the target cell is met or not to the terminal;

the method comprises the steps that after the terminal receives information which is sent by a base station of a cell where the terminal is located and used for triggering the terminal to start judging whether switching conditions are met, the terminal starts to judge whether the switching conditions for switching from the cell where the terminal is located to a target cell are met, the information represents that the cell which is allowed to be switched exists, the terminal judges that the switching conditions are met when at least one of a plurality of preset conditions occurs, the plurality of preset conditions comprise radio link failure, failure of sending uplink data to a source base station for continuous preset times by the terminal, failure rate of sending the uplink data to the source base station within preset time is higher than a preset threshold value, and signal intensity of the target cell is higher than signal intensity of the cell where the terminal is located currently.

4. The cell switching method according to claim 3, wherein the information for triggering the terminal to start determining whether the switching condition from the current cell to the target cell is satisfied comprises: and indicating the target base station to allocate the resources for accessing the target cell to the terminal.

5. The method of claim 3 or 4, further comprising:

6. The method of any of claims 3 to 4, further comprising:

the source base station starts timing after receiving the cell measurement information sent by the terminal or after sending the switching preparation request to the target base station;

and when the timing reaches a first preset time length, if the source base station does not receive any message indicating that the terminal is successfully accessed or switched to the target cell, the source base station sends information for indicating to release the resources allocated to the terminal to all the target base stations.

7. A method according to any of claims 3 to 4, characterized in that the method comprises:

the source base station sends timing information to the target base station; the timing information indicates a second preset duration for the target base station to wait for releasing the resources allocated to the terminal.

8. A terminal, characterized in that the terminal comprises a processor and a transceiver;

after the transceiver receives information which is sent by a base station of a current cell and used for triggering the terminal to start judging whether a switching condition is met, the processor is used for starting judging whether the switching condition for switching the current cell to a target cell is met, wherein the information represents that the cell which allows switching is determined, and the processor judges that the switching condition is met when at least one of a plurality of preset conditions occurs, wherein the plurality of preset conditions comprise that a wireless link fails, the terminal fails to send uplink data to the base station of the current cell for continuous preset times, the failure rate of the terminal sending the uplink data to the base station of the current cell within a preset time is higher than a preset threshold value, and the signal intensity of the target cell is higher than the signal intensity of the cell in which the terminal is currently located;

the transceiver is configured to send an access request to a target base station when the handover condition is satisfied, where the target base station is a base station of the target cell.

9. The terminal of claim 8, wherein the transceiver is further configured to receive indication information sent by the base station of the current cell, where the indication information indicates resources allocated by the target base station for the terminal to access the target cell;

the transceiver is further specifically configured to send an access request to the target base station according to the resource allocated by the target base station.

10. A base station device, characterized in that the base station device comprises a processor and a transceiver;

the transceiver is used for receiving cell measurement information sent by a terminal;

the processor is used for controlling the transceiver to send a switching preparation request to the base station of each alternative cell after the transceiver receives the cell measurement information;

the transceiver is further configured to receive handover preparation confirmation information fed back by a target base station, where the target base station is a base station of a target cell, and the target cell is an alternative cell that allows terminal handover among the alternative cells;

the processor is further configured to control the transceiver to send, to the terminal, information for triggering the terminal to start determining whether a handover condition for switching from a current cell to the target cell is satisfied, after the transceiver receives the handover preparation confirmation information;

the method comprises the steps that after the terminal receives information which is sent by a base station of a cell where the terminal is located and used for triggering the terminal to start judging whether the switching condition is met, the terminal starts to judge whether the switching condition is met or not, the switching condition is switched from the cell where the terminal is located to a target cell, the information represents that the cell which is allowed to be switched is determined, when at least one of a plurality of preset conditions occurs, the terminal judges that the switching condition is met, the preset conditions comprise radio link failure, failure of sending uplink data to the base station equipment for continuous preset times by the terminal, failure rate of sending the uplink data to the base station equipment within preset time is higher than a preset threshold value, and signal intensity of the target cell is higher than signal intensity of the cell where the terminal is located currently.

11. The base station device of claim 10, wherein the information for triggering the terminal to start determining whether a handover condition for handover from the current cell to the target cell is satisfied comprises: and indicating the target base station to allocate the resources for accessing the target cell to the terminal.

12. The base station device of claim 10 or 11, wherein the processor is further configured to: and after the terminal is successfully accessed or switched, controlling the transceiver to send information for indicating to release the resources allocated to the terminal to other target base stations except the base station where the cell successfully accessed or switched by the terminal is located.

13. The base station device of any of claims 10 to 11, wherein the processor is further configured to: after the transceiver receives cell measurement information sent by a terminal or after the transceiver sends the handover preparation request to the target base station, starting a timer to start timing;

when the timing reaches a first preset time length, if the transceiver has not received any message indicating that the terminal is successfully accessed or switched to the target cell, the processor is further configured to control the transceiver to send information indicating to release the resource allocated to the terminal to all the target base stations.

14. The base station apparatus of any of claims 10 to 11, wherein the transceiver is further configured to transmit timing information to the target base station; the timing information indicates a second preset duration for the target base station to wait for releasing the resources allocated to the terminal.

15. A communication system, characterized in that the communication system comprises a terminal according to any of claims 8 to 9 and a base station device according to any of claims 10 to 14.